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Systematic review and meta-analysis of the participation rates in clinical trials evaluating non-pharmacological interventions for psychosis

Poor retention of participants in randomised controlled trials (RCTs) is a commonly recognised issue. Attrition rates in studies across different disciplines have been reported to vary from 5% to 70%. There is no systematic evidence reporting attrition rates specifically in trials involving people with severe and fluctuating mental health conditions.

To purpose of this review was to synthesise the reported retention rates in RCTs evaluating non-pharmacological interventions for psychosis and identify study characteristics associated with high dropout.

Five key electronic databases and key journals were systematically searched to identify studies published between 1996 and 2015. The search included large scale RCTs (n≥100 at baseline) including adults with psychosis receiving non-pharmacological interventions. Data extraction included participant flow information reported in the Consolidated Standards of Reporting Trials (CONSORT) statement or flow diagram. Random effects logistic regression analysis was conducted to examine effects of key study characteristics on participation rates.

62 papers were included in the review. This paper will discuss the participation rates reported in RCTs, the quality of reporting in publications, and the study characteristics that predict participation rates.

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Correspondence to Paulina Szymczynska.

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This article is published under license to BioMed Central Ltd. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. The Creative Commons Public Domain Dedication waiver ( applies to the data made available in this article, unless otherwise stated.

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Szymczynska, P., Walsh, S. & Priebe, S. Systematic review and meta-analysis of the participation rates in clinical trials evaluating non-pharmacological interventions for psychosis. Trials 16, P169 (2015).

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  • Participation Rate
  • Retention Rate
  • Mental Health Condition
  • Study Characteristic
  • Attrition Rate


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